Conventionally, an X-ray apparatus includes an X-raying table having a top board for supporting an inspection object M, an X-ray tube for emitting X-rays toward the inspection object (for irradiation), and an X-ray detector disposed opposite the X-ray tube for detecting X-rays transmitted through the inspection object. The X-ray tube is held by an X-ray tube holding device suspended from a ceiling, for example. The X-ray detector is mounted in the X-raying table and in a position opposed to the X-ray tube across the top board.
When X-raying the whole spine or a whole lower limb of the inspection object with this X-ray apparatus, these cannot be fitted at a time in the X-ray detecting area of the X-ray detector. Therefore, a technique called long-size radiography is used (see Patent Documents 1 and 2, for example). Long-length radiography is carried out as follows. First, radiography is carried out while translating the X-ray tube and X-ray detector along the inspection object to obtain a plurality of consecutive X-ray images. Then, one long image is created by splicing together the plurality of X-ray images obtained.
Further, long-size radiography includes a technique called slot radiography which obtains a long image by contracting emitted X-rays to a slit shape (also called a slot shape) (see Patent Document 3 and Nonpatent Document 1, for example). This technique obtains a long image by contracting X-rays to the slit shape, carrying out continuous radiography while translating the X-ray tube and X-ray detector to obtain X-ray images, and splicing together the plurality of X-ray images. The X-rays contracted to the slit shape can be regarded as a parallel X-ray emission from infinity, which can obtain a long image free of distortion. Further, slot radiography can suppress the influence of scattered X-rays, and can therefore obtain a high definition long image.